1. Field of the Invention
The present invention relates to a flat panel display device and method thereof, and more particularly, to a flat panel display device preventing oxidation/corrosion of an emission element due to harmful material such as oxygen/moisture, thereby enhancing the reliability of the product and prolonging the lifetime, and a method of protecting the display area of a flat panel display device from moisture and oxygen.
2. Description of the Related Art
FIG. 1 is a cross-sectional view of a conventional flat panel display device and in particular, an organic light-emitting display device disclosed in U.S. Pat. No. 6,624,568. Referring to FIG. 1, an organic light-emitting device (“OLED”) 20 is formed over a substrate 11. While not shown in FIG. 1, the OLED 20 has a structure in which a first electrode layer constituting an anode injecting holes, an organic film emitting light by recombination of holes and electrons, and a second electrode layer constituting a cathode injecting electrons are deposited successively. In the organic film, light is generated by the recombination of holes and electrons injected from the respective first and second electrode layers. To this end, the first electrode layer may be formed of a high work function material and the second electrode layer be formed of a low work function material. The second electrode layer is highly active and chemically unstable and thus reacts easily with moisture or oxygen from the outside air causing oxidization or corrosion. With the permeation of moisture or oxygen into the organic film, the emission characteristic of the emission film is degraded due to the changed crystalline structure of the emission film. According to the conventional art, at the upper and lower portions of the OLED 20, a multi-layered protective layer, in which high-density layers 41 and planarizing layers 42 are arranged alternately, is formed. The high-density layers 41 are formed of dense atomic array material to prevent the permeation of oxygen/moisture from the outside. Also, an absorbing layer 60 absorbing oxygen/moisture is formed between the planarizing layers 42 to absorb the permeated material and the absorbing layer 60 includes a metal element having good reactivity to oxygen/moisture.
According to the conventional art, an active metal element, having a same material as the absorbing layer 60, must be made into a paste type suitable for coating to form a thin film of the absorbing layer 60 and thus an additional material such as a vehicle or a binder is required. Also, because the absorbing layer 60 is formed to be a thin film type and the amount of the active metal element contained in the absorbing layer 60 is limited below a desired level, the absorbing layer 60 is saturated early and does not function effectively and thus there are problems due to the permeation of harmful material.